The present invention relates to a bar code reader and more particularly to a high density bar code reader.
Bar code scanners and readers are intrinsically tied to the bar code being read. A bar code is typically a printed series of bars having either uniform or varying widths interposed upon a white or contrasting background. At the present, approximately 50 commercial bar code systems are being used; of these, only four bar code systems are principally used.
The bar code target, the series of bars, is formulated so as to communicate a series of binary data which is indicative of some information for use by a computer, calculator, or the like. The Universal Product Code (UPC) has been widely accepted and utilized by the food industry to mark products. At the point of sale, the bar code target is moved relative to a scanner which reads the bar code and is thereby informed of the product identification. The product identification is used to formulate or compute the price of the product.
One method to increase the data density of bar code, is to have the bar size decreased from 20 thousandths of an inch standard to 5 thousandths of an inch (mil) widths so as to allow more compaction of the data string. This width though is extremely difficult to print and additionally requires a more complex optical system for reading. The costs of printing and optical requirements have made this solution unreasonable.
For a good review of the bar code use and applications, refer to "Reference Guide" for "Bar Code Scanning" by MSI Data Corporation, copyright 1980, incorporated hereinto by reference. This manual focuses on seven bar codes and explains the basics of bar code structures and optical wand scanners and their functions.
None of the current bar codes are capable of obtaining a data density sufficient for many uses. Their restraint lies in the fact that although reducing the width of the bar size itself does increase the density, the associated problems with the optical reader make it economically infeasible to utilize a 5 mil or smaller bar size.